Exotic State of Magnetism Probed in the Mineral Herbertsmithite

The details of an exotic state of fluid magnetism known as quantum spin liquid have been documented in a new analysis in the journal Physical Review Letters.

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This unique state of magnetism is observed in a mineral called herbertsmithite. Unlike the conventional magnetism found in ferromagnets, where all magnetic forces align in the same direction, reinforcing each other, and anti-ferromagnets, where adjacent magnetic elements align in opposite directions to produce a canceling effect - the magnetic properties of herbertsmithite are completely different to, conventional magnetism.

In herbertsmithite, the magnetic elements constantly fluctuate in a state of fluid magnetism that researchers say could lead to breakthroughs in quantum computing and novel solutions to some of physics' most complicated problems.

Quantum spin-liquid magnetism have been known to science for some time, but there has never been a detailed analysis of how the electrons in herbertsmithite respond to light -- a key to establishing which of several competing theories about the mineral is correct.

By using laser pulses just a trillionth of a second long, researchers from MIT, Boston College and Harvard University successfully measured how the material's electrons respond to light. The researchers found a "signature in the optical conductivity of the spin-liquid state that reflects the influence of magnetism on the motion of electrons," which they say supports a set of theoretical predictions that have not previously been demonstrated experimentally.

"Theorists have provided a number of theories on how a spin-liquid state could be formed in herbertsmithite," said Daniel Pilon, a graduate student who contributed to the experiments. "But to date there has been no experiment that directly distinguishes among them. We believe that our experiment has provided the first direct evidence for the realization of one of these theoretical models in herbertsmithite."

Nuh Gedik, study co-author and associate professor of physics at MIT, said at this stage it is difficult to predict future potential applications for the research, but it "could help us to solve some very complicated problems in physics, particularly high-temperature superconductivity, which might eventually lead to important applications."

Pilon added: "This work might also be useful for the development of quantum computing."